Today, we have released a new node node-red-contrib-prometheus-exporter that allows you to define your own Prometheus metrics and to expose them from within flows.
We are using the node at docoyo for our own product development, but are happy to share it with you. I saw that there have been a couple of people asking for this functionality this year. So I hope that it will be helpful to some of you.
Happy to receive feedback and ideas for further development.